Consumable guide tube

ABSTRACT

A consumable guide tube includes a thin first elongated strip, a second elongated strip and a plurality of insulators. The thin first elongated strip has a front face having at least one longitudinal channel and a back face. The second elongated strip has a front face configured to be coupled to the front face of the first elongated strip and a back face. The plurality of insulator modules are deposited on the back faces of the thin first elongated strip and the second elongated strip. Preferably, the thin first elongated strip is a low carbon cold-rolled steel strip, and the second elongated strip is a low carbon hot-rolled steel strip. The guide tube is also configured to include two or more longitudinal channels.

The present application is a Continuation of: 1) provisional patentapplication Ser. No. 60/175,574, filed on Jan. 11, 2000, titled a“System and Method for Employing a Guide Tube in an Electroslag Weld”,2) provisional patent application Ser. No. 60/188,782 filed on Mar. 13,2000 and titled “Welding System”, 3) and non-provisional patentapplication Ser. No. 09/757,738, filed Jan. 9, 2001, now U.S. Pat. No.7,148,443, issued Dec. 12, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a consumable guide tube used inwelding. More particularly, the guide tube of the present inventionprovides an economical and cost effective solution for guide tubemanufacturing.

2. Background Art

Generally, the electroslag method generally involves bringing the endsof two substrates or workpieces together to create a gap between theends of the plates. Welding shoes, which are generally made of copper,are then placed on each side of the gap to form a cavity between theplates and welding shoes. A steel guide tube is placed into the weldingcavity for feeding a single welding wire into the cavity.

Current is then conducted through an electrode, comprising the guidetube and the welding wire, to the parent substrate material and an arcis struck in the bottom of the welding cavity. A granular flux issprinkled into the welding cavity and melts under the influence of thearc to form a molten slag. As wire continues to feed into the cavity,the level of the molten slag rises to come in contact with the bottom ofthe guide tube and the welding arc is extinguished. The electric currentpassing between the electrode and the substrates is conducted though themolten slag. Heat generated by the molten slag melts the electrode,welding wire, and substrates to generate a molten metal puddle. Sincethe molten metal is heavier than the molten slag, the metal gravitatesto the bottom and the slag floats on top. During the welding processcurrent and voltage are transmitted to the molten slag and metal weldpuddle. A relatively deep weld metal puddle is generated, which includesa relatively high percentage of parent material. As the weld progressesvertically, the bottom of the metal puddle cools and fuses thesubstrates to form an electroslag weld.

Welding wire is continually fed into the molten slag, and the weldcontinues to progress vertically until the welding cavity is filled withmolten metal. As the weld rises, the molten slag pool continues tomelt-off of the bottom of the guide tube. The guide tube is consumableand contributes to the weld metal. The copper shoes retain the moltenslag and weld metal, and are removed when the weld is completed. Acomprehensive description of electroslag welding is provided in theAmerican Welding Society Welding Handbook, eighth edition, which isincorporated by reference.

A recent improvement to the traditional electroslag method has beendeveloped by the Oregon Graduate Institute (OGI) and is known as theNarrow Gap Improvement electroslag welding method (NGI-ESW). OGI'sNGI-ESW process advocates employing a narrow gap of approximately 0.75of an inch between the substrates. Traditionally, a 1¼ inch gap betweenthe substrates was used. Much like the previously described electroslagprocess, OGI advocates using a traditional guide tube design which feedsonly a single wire and which does not oscillate.

Referring to FIG. 1 a, a traditional winged guide tube 10 having astandard piece of heavy-wall metal tubing with wings 12. The wings 12are separately welded to the heavy-wall metal tubing 13. The internaldiameter of the metal tubing 13 is approximately ⅛ of an inch and theouter diameter is approximately ⅜ of an inch. The wings 12 aretack-welded 14 to the edges of the metal tubing as shown in FIG. 1 a.

Referring to FIG. 1 b, there is shown a cross-sectional view of thewinged guide tube 10 of FIG. 1 a. For illustrative purposes the tackwelds 14 for the winced guide tube 10 are shown.

The wings 10 are used to spread the current across the molten slag.During the welding process, the weld puddle generated by OGI NGI-ESWelectroslag method is deep and wide. This deep and wide weld puddle hasa high percentage of substrate metal in the weld metal. Therefore, thelimitation of OGI's NGI-ESW method is that it fails to maintain ashallow weld puddle at higher welding currents. If a single welding wileis used, the puddle becomes deeper with the increase in weld speed. Ifthe puddle becomes too deep, the grain formation creates by thesolidifying weld metal can make the resulting weld more crack sensitive.

Referring to FIG. 1 c, there is shown a cross sectional view of a webbedguide tube which has a plate 20 welded between a first metal tubing 22and second metal tubing 23.

Referring to FIG. 1 d there is shown a combination winged and webbedguide tube 25 having wrings 26 and 27 welded to metal tubing 28 a and 28b, respectively. Additionally webs 29 a and 29 b are welded to tubing 30and metal tubing 28 a and 28 b.

Referring to FIG. 1 e, there is shown another guide tube described inCanadian Patent 886,174 issued to Norcross and titled ElectroslagWelding Nozzle and Process. The Norcross '174 patent describes anupwardly extending stationary consumable metallic nozzle having ametallic guide tube through which a single welding wire is introduced.The consumable metallic nozzle has wing bars extending out oil two sidesof the guide tube and an adhering coating of flux covering the nozzle,which melts off as the weld rises, and as the nozzle itself melts off.In an electroslag process using a narrow welding gap, i.e. NGI-ESW, thethin layer of flux used by Norcross would generate an arc between theguide tube electrode and the substrate or welding shoes. Furthermore, itthe thick plates used by Norcross would draw too much amperage.

The drawback of the current design of guide tubes is that they must becustom designed for a particular application. This customization makesthe guide tubes expensive to manufacture. More specifically, tubing mustbe purchased, and the plates must be sheared or the plates must beindividually purchased. Then the plates must be welded to the tubing tomeet relatively high tolerances. These guide tubes are very timeconsuming and expensive to manufacture.

Another drawback of the present guide tube designs is that they restrictthemselves to using guide tubes which are “wedged” in place and do notoscillate. Even though multiple wile guide tube designs are taught,these guide tubes are made from tubing with wings and webs to join themtogether. In each case the guide tubes are “wedged” in tightly and arenot configured to oscillate. Therefore, there is a need for a guide tubedesign which facilitates oscillation.

A final drawback to present welding methods employing a consumable guidetube is that they fail to maintain a shallow weld puddle at higherwelding currents, and become crack sensitive at higher weld speeds(vertical rate of rise). When using a fixed guide tube, welding voltagemust be increased to increase the diameter of the weld. To make surethat the weld penetrates all four corners of the weld cavity, thevoltage must be substantially increased. This causes wider weld puddles,more substrate dilution, and larger heat affected zone (HAZ) in thesubstrate. This large HAZ lowers the physical characteristics of thesubstrate. Oscillation is used to spreads the weld puddle, instead ofvoltage. This results in a much smaller weld puddle, and HAZ, and betterphysical characteristics of the substrate with the oscillating multiwireguide tube.

Therefore, it would be beneficial to provide a standard off-the-shelfguide tube that can be used to perform a variety of welds.

It would also be beneficial to provide a consumable guide tube that issimple and economical to manufacture.

Additionally, it would be beneficial to provide a consumable guide tubewhich can feed at least two welding wires.

Furthermore it would be beneficial to provide a guide tube that operatesin electroslag process that uses oscillation.

Further still it would be beneficial to provide a guide tube withinsulator modules which prevent arcing with the substrates and thewelding shoes.

Further still, it would be beneficial to provide a guide tube withinsulator modules which do not increase the depth of the molten slag.

Finally, it would be beneficial to provide a consumable guide tube thatcan sustain a shallow weld puddle so that the resulting weld is lesscrack prone and impact values for the weld are increased.

SUMMARY OF THE INVENTION

The present invention is a guide tube which guides at least one weldingwires into a welding cavity, transmits welding amperage, voltage andcurrent to said welding wire, and is consumed during the weldingprocess. Preferably, the welding process is the electroslag weldingprocess. The guide tube comprises a first elongated metal strip having afront face and a back face and a second elongated metal strip having afront face and a back face. At least one longitudinal channel is definedon the front face of the first elongated metal strip. The front face ofthe first elongated metal strip is joined to the front face of thesecond elongated metal strip. The at least one channel is positioned toreceive at least one welding wire. Preferably, the first elongated metalstrip is a thinner metal strip than the second elongated metal strip.Alternatively, the first elongated strip is the same thickness as thesecond elongated strip.

A plurality of insulator modules are attached to the back face of thefirst elongated metal strip and the back face of the second elongatedmetal strip at incremental stages. Preferably, the plurality ofinsulator modules are positioned to prevent arcing between the guidetube electrode and the substrate material and the copper shoes.Preferably, the insulator modules do not increase the depth of themolten slag puddle because the molten slag contribution from theinsulator modules matches or is less than the molten slag which is lostfrom deposition on the welding shoes.

Additionally, the guide tube provides for the production of anelectroslag weld which has a reduced based substrate material in theelectroslag weld and a smaller heat affected zone. More specifically thepresent invention uses the guide tube described above to weld metalsubstrates by positioning two substrates to define a substantiallynarrower gap, and then positioning a pair of welding shoes adjacent thegap to define a welding cavity. The guide tube is then positioned withinthe weld cavity to feed at least one welding wire. Sufficient amperageand voltage is provided to the guide tube and welding wire to be capableof striking an arc against the substrates. The welding cavity is thenfilled with flux, which melts and generates a molten slag thatextinguishes the arc. The molten slag melts the guide tube and thewelding wire and generates a molten weld metal pool. The guide tube isthen oscillated. The combined oscillation and the preferable feeding ofat least two wires generates a shallow molten metal pool depth. Theelectrical operating parameters and wire feed rate are controlled tomaintain a shallow weld puddle. The resulting weld between thesubstrates is an impact resistant weld.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 a is a prior art winged guide tube.

FIG. 1 b is a cross-sectional view of the winged guide tube of FIG. 1 a.

FIG. 1 c is cross-sectional view of a prior art webbed guide tube.

FIG. 1 d is a cross-sectional view of a combination winged and webbedguide tube.

FIG. 1 e is another prior art guide tube.

FIG. 2 a is a top view of a dual wire feed guide tube in which only onestrip is roll formed and the other strip is flat.

FIG. 2 b is a cross-section of FIG. 2 a.

FIG. 3 a is a guide tube within a weld cavity with insulators.

FIG. 3 b is an isometric view of a single wire consumable guide tube.

FIG. 3 c is an isometric view of a dual wire consumable guide tube.

FIG. 4 is a side view of an embodiment in which three strips are joinedsuch that one strip is flat and the other two strips are roll formed.

FIG. 5 is alternative embodiments of guide tube designs.

FIG. 6 a is a top view of a single strip milled to receive two wirefeeds with staged insulator modules.

FIG. 6 b is a cross-sectional view of FIG. 2 a.

FIG. 6 c is a top view of two single strips which are joined together.

FIG. 6 d is a cross-sectional view of FIG. 2 c.

FIG. 7 a is a side view of a guide tube having insulator modules on theback side of the joined strips

FIG. 7 b is a side view of a guide tube having insulator modules on theback side of the joined strips and on the end of the wings of the guidetube.

FIG. 7 c is a side of an alternative embodiment in which three stripsare joined together.

FIG. 8 is a method for using the guide tube in an electroslag process.

FIG. 9 is a method for manufacturing the guide tube.

DETAILED DESCRIPTION OF THE INVENTION

Persons of ordinary skill in the art will appreciate that the followingdescription of the present invention is illustrative only and not in anyway limiting. Other embodiments of the invention will readily suggestthemselves to such skilled persons in the art having the benefit of thisdisclosure.

The present guide tube design provides a solution which minimizes thecost of a consumable guide tube for welding and maximizes the quality ofthe surrounding weld. The application of the consumable guide tubedisclosed herein is based upon Electroslag welding methods. Inparticular, the guide tube described herein is employed in anoscillating Electroslag welding process which is described in patentapplication Ser. No. 09/058,741, U.S. Pat. No. 6,297,472, titled“Welding System and Method” which is hereby incorporated by reference.However, it shall be appreciated by those skilled in the art having thebenefit of this disclosure that the principles of guide tube designdescribed in this patent may also be applied to other welding methods.

Electroslag welding uses a large power supply to generate a molten fluxwhich drives the electroslag process. In an environment having aconstant voltage power supply, the constant voltage power supply drawscurrent according to the load placed on the power supply. In the case ofelectroslag welding, the inventor found that the load is determined bythe cross-sectional area of the guide tube which is exposed to themolten flux puddle. The inventors have found that the cross-sectionalarea of the guide tube affects the load on the welding power supply. Thelarger the cross-sectional area that is immersed in the molten fluxpuddle the higher the current draw (when using a constant voltage powersupply). If the cross-sectional area immersed in the molten flux puddlebecomes too great, the minimum current produced by the constant voltagepower supply will become too high to produce an acceptable weld. Ifoscillation cannot be used, the guide tube width and thickness has to bespecifically designed to match the thickness of the strips to be welded.

During experimental efforts undertaken by the inventor, a guide tubehaving two 4-inch wide metal strips which were each ¼-inch thick wassubjected to the electrical loading for Electroslag welding. Thecross-sectional area of the guide tube was 2 square inches. The load wasso great on the was 2 square inch guide tube that when the guide tubemade contact with the slag puddle the amperage of the power supply couldnot be reduced below 2500-Amps. To solve this problem the plates weremade thinner. For a 4-inch wide weld, the preferred guide tube designincluded a current carrying plate being ⅛ inch thick fixedly coupled toa wire guide plate having a 22-gauge material. It shall be appreciatedthat the 22-gauge plate equivalent is a 0.025 inch plate. Thecross-sectional area of the preferred guide tube for a 4-inch weld was0.6 square inches.

By way of example and not of limitation, if a weld which was 8-inch wideis undertaken, then the guide tube dimensions for a 4-inch weld drawstoo high a load because the cross-sectional area would be too high, e.g.1.2 inches^2. To adequately bring down the amperage, the cross-sectionalarea for a guide tube making an 8-inch weld would be reduced to having acurrent carrying strip of 1/16″ thick, and a wire guide strip being madeof a 22-guage material. Therefore, the cross-sectional area of thepreferred guide tube for an 8-in weld was 0.7 inches^2.

An illustrative example of this guide tube design is provided in FIG. 2a and FIG. 2 b which show that a similar cross-sectional area can begenerated by varying the width and thickness of the flat strip. By wayof example, a 1 inch wide strip which is 3/16 inch thick has across-sectional area of 0.1875 inches^2. The same cross sectional areacan be achieved with a 2 inch wide strip which is 3/32 inch thick.Additionally, the same cross-sectional are can be obtained for a 3 inchwide strip having a 1/16 inch thick strip. Note, that in thisapproximation, the thin roll formed strip contribution to thecross-sectional area is assumed to be negligible. The benefit of thisdesign is that by maintaining the same cross-sectional area the loaddrawn by each of guide tube is more easily controlled as describedabove.

FIG. 2 a is a front view of a dual wire feed guide tube in which onlyone strip is roll-formed and the other strip is flat. In thisembodiment, the guide tube 120 comprises a flat strip 122 with insulatormodules 124, 126, 128 and 130 which also are referred to as insulatorbuttons. The insulator modules are positioned at incremental stages. Athin strip 136 is roll formed to receive welding wire 132 and 134.Insulator modules 138 and 140 also are coupled to the thin strip 136.Persons with ordinary skill in the art will appreciate that the thinstrip is coupled to the flat strip using well known techniques. Theinsulator modules are approximately ¼ inch thick but also can be madethinner. The insulator modules prevent arcing between the guide tubeelectrode and the substrates or the welding shoes.

FIG. 2 b is a cross-sectional view of FIG. 2 a. The thin strip 136 isroll formed into two triangular wedges which receive the welding wires132 and 134. The insulating modules 138 and 140 are attached to the backof thin strip 136 at the triangular wedge position. By way of exampleand not of limitation the a guide tube shown in FIG. 2 a and FIG. 2 b ismade of one flat strip having a variable thickness from 1/16^(TH) to¼^(TH) of an inch and the thin roll formed strip has a thickness rangingfrom 22 to 28 AWG.

FIG. 3 a is shows a guide tube within a weld cavity. A welding gap iscreated by placing two substrates or workpieces 220 and 222 next to oneanother. Two welding shoes 224 and 226 are placed adjacent the weldinggap to define a welding cavity. The guide tube 228 is placed within thewelding cavity. During operation the guide tube 228 can be oscillated.Insulator modules 230 and 232 are disposed on the edges of the guidetube to prevent short circuiting with the substrates 220 and 222 and thewelding shoes 224 and 226.

The strips 234 and 236 of the consumable guide tube 228 comprise a lowcarbon steel, such as a 1008 carbon steel. High carbon steels are notdesirable because they harden the weld and makes it less ductile.

In operation, the guide tube 228 feeds at least two welding wires 236and 238 into the molten slag bath. The guide tube 228 and welding wires235 and 238 act as an electrode which transmits the necessary power oramperage to maintain a molten slag bath. The welding wires 235 and 238perform the function of feeding more mass into the weld puddle; thisadditional mass acts as a heat sink for the molten weld puddle andmaintains a relatively shallow weld puddle.

A variety of benefits are associated with this shallow weld metalpuddle. The benefits include providing a higher form factor, which ismore crack resistant than electroslag welds made with processes andprocedures requiring deeper molten metal weld pools. The deeper themolten weld metal puddle (not the molten flux puddle) the lower the formfactor, and the more crack prone the weld becomes. The shallower themolten weld metal puddle, the higher the form factor, and the more crackresistant the weld becomes. The weld puddle can be kept shallow by usinga metal-cored wire instead of a solid wire. The thin metal sheath of acored wire tends to create a shallower metal puddle. Additionally, theweld puddle can be kept shallow by increasing the number of wires usedto make the weld (at any given current) will make the weld metal puddleshallower. By way of example and not of limitaition, 2 wires at1000-amps create a shallower puddle than 1 wire at 1000-amps. 4-wires at1000-amps create a shallower puddle than 2 wires at 1000-amps, and soon. Furthermore, the weld puddle can be kept shallow by using anoscillating guide tube to spread the weld puddle, instead of usinghigher voltages to spread the weld puddle, creates a shallower puddle.Further still, the welding puddle can be kept shallow by using a smallergap so that the weld cavity fills faster, thereby creating a shallowerpuddle. Since the vertical-rate-of-rise is faster, more base metal hasbe heated faster—taking heat away from the weld puddle, and making itshallower. Finally, the welding puddle can be kept shallow by usingsmaller diameter wires ( 1/16″ dia instead of ⅛″ or 3/32″). At any givencurrent, a smaller diameter wire will yield a shallower puddle than alarger diameter wire. For instance, a weld made with a 1/16″ dia wire,at 1000-amps, will produce a shallower puddle than a 3/32″ dia wire at1000-amps. A 3/32″ dia wire will produce a shallower puddle than a ⅛″dia wire, and so on.

The benefits of having a shallower weld puddle are closely associated tothe reduction of the heat affected zone. In the case of electroslagwelding, a large heat input and a relatively slow travel speed generatesa relatively deep weld puddle which in turn creates a very large heataffected zone. This large heat affected zone generally has a very lowcharpy impact value and provides the weakest portion of the electroslagweld. The weld metal impact values can be held high by adding alloyingmaterials such as nickel, to increase the impact values in the resultantweld metal, but these alloy additions do nothing to increase the impactvalues metal in the heat affected zone. In order to minimize the heataffected zone it is preferable that the guide tube design include amultiple wire system to provide shallower weld puddles. It is alsopreferable to design narrow guide tubes configured to “guide” multiplewire systems. Preferably insulators which allow for guide tubeoscillation also help reduce the size of the heat affected zone.Furthermore, a guide tube can be made to operate in a weld gap smallerthan the ¾″ NGI-ESW weld gap.

It shall be appreciated by those skilled in the art having the benefitof this disclosure that a thin guide tube can be manufactured by makingthe insulator buttons “shorter”, i.e. making the insulator buttonssmaller than ¼″, e.g. 3/16″. Additionally, the use of thinner strips forthe guide tube can also be used to make the guide tube thinner. The thinguide tube is used in welding gaps which are smaller than the ¾″ weldgap used in the NGI-ESW method described above.

In operation, flux deposition must be regulated carefully. Recall thatflux is converted to a molten slag, and the molten slag bath acts as afloating molten resistor which is heated by resisting the flow ofcurrent—just like the nichrome wire in a toaster is heated by resistingthe flow of current. If the slag bath becomes too deep the molten slagbath dissipates heat over a larger surface of the substrate. This largersurface cools the molten flux bath and the flux puddle becomes colder.If the slag bath temperature becomes too low, the molten slag will notmelt the wire as efficiently. This can cause incomplete penetration ofthe weld metal to the substrate, resulting in a defective weld. If themolten flux puddle becomes too shallow, the puddle is not required toheat as much surface area of the substrate, which causes the puddle tobecome very hot. This rise in flux puddle temperature can cause theguide tube to burn off above the flux puddle, inducing arcing betweenthe electrode and the substrate or the weld puddle. As shown in FIG. 3,when the insulator modules 230 and 232 are melted, they contribute verylittle volume to the molten flux puddle. Insulator modules 230 and 232are spaced at intervals, which contribute to the molten slag bath at arate which is less than the rate at which the molten slag is lost fromplating against the copper shoes 224 and 226. If the molten in the weldcavity becomes too low, an operator can hear the slag bath “popping” andsimply can add additional flux manually. If automatic flux dispensing isused, the electronic control senses the current and voltages swingsgenerated by a shallow puddle. The controller automatically adds flux tothe puddle until the current and voltage swings are reduced to anacceptable level. This method will maintain the flux at a relativelyconstant level.

However, in certain welds such as box column or keyhole welds, there areno copper shoes and hence no loss of molten slag. In such instances,small “buttons” of insulators are used. These small buttons add minimalamounts of flux to the molten slag bath and thereby permit tall weldswithout appreciably increasing the depth of the flux. This corrects theproblem generated by methods which coat the entire guide tube. When theentire guide tube is coated, it generates a molten slag bath which istoo deep, thereby causing incomplete fusion in a box column or keyholeweld. Therefore, in a box column or keyhole weld, it would not bepossible to use a guide tube with flux enveloped around the guide tube.The flux in the guide tube would cause the molten flux puddle to becomedeeper and deeper as the flux melted from the guide tube when the fluxlevel became too deep. The weld cavity would experience such asincomplete fusion and flux inclusion.

Adding at least two wire feeds in the present process decreases dilutionof the parent material and does not dilute the nickel concentration. Inthe Arcmatic™ process, at least two wires are used to weld the material.Even for one-inch strip, the novel Electroslag process uses two wires.The reason is for any given amperage you are feeding more mass into thestrip by doubling the amount of mass of welding wires. This additionalmass acts as a heat sink, which effectively “dries” up the molten weldpuddle and maintains a shallow puddle depth. The shallower puddle depthmaintains a higher form factor, which is more crack-resistant. Thebenefit of using more feed wires ius that it keeps the puddle shallowand more crack-resistant.

FIG. 3 b is an isometric view of a butt weld fixture for Electroslagwelding 240 having a single wire consumable guide tube 242 disposedwithin a gap defined by two substrates and two copper shoes. Moreparticularly, the single wire guide tube 242 is made from two separatestrips of low-carbon hot rolled steel. The first steel strip 243 a isflat, and the second steel strip 243 b has one longitudinal channelrolled into the surface of the strip. The first steel strip 243 a isplaced on the second steel strip 243 b and the one longitudinal channelprovides a ⅛ inch diameter cavity which receives a 3/32 inch diameterwelding wire. The strips 243 a and 243 b are spot welded to make thesingle wire consumable guide tube 242.

A plurality of insulator modules 244 are attached to either side of theguide tube 242 which interfaces with either the substrates 246 or withthe copper shoes 247. It shall be appreciated by those skilled in theart having the benefit of this disclosure that copper shoes are used asretaining walls for the welding puddle and that copper shoes aregenerally hollow and water cooled. Therefore, copper shoes for purposesof this patent application is used generally to refer to a device whichsurrounds the weld puddle during a weld having two substrates which arebeing welded together. Preferably, these button insulators are disposedon the edge of the guide tube 242 to prevent arcing with either thesubstrates 246 or the copper shoes 247. It shall be appreciated by thoseof ordinary skill in the art that these button insulators are glued onto the surface with a glue or binding agent. The button insulators aremade from the same flux material used during the electroslag weldingprocess. Preferably, the button insulators are beveled and the largediameter portion of the insulator button is attached to the guide tubeat intervals of 4 to 6 inches. When the molten flux puddle reaches theglued on button insulator, the insulator melts and becomes part of themolten flux puddle. The buttons are small enough that they cause nosignificant change to the resistance, chemistry, or depth of the weldpuddle.

By way of example, the two hot rolled strips are 1/16″ thick and whenwelded together provide a guide tube which is ⅛″ thick. The buttoninsulators are approximately ¼″ thick and when attached to the guidetube the guide tube width is ⅝″. The ⅝″ guide tube may then be employedinside a ¾″ narrow gap weld process as described above with a ⅛″ ofclearance. This clearance allows the guide tube to be oscillated. If theweld process requires the guide tube to be fixed, rolled alumina stripsare wedded on either side of the guide tube to eliminate the ⅛″clearance.

It shall be appreciated by those skilled in the art that guide tubes maybe manufactured with one or more longitudinal channels, and that guidetubes may be manufactured for operation at various widths.

FIG. 3 c is an isometric view of a butt weld fixture for electroslagwelding 248 having a dual wire consumable guide tube 249 disposed withina gap defined by two substrates and two copper shoes. The dual wireconsumable guide tube 249 is similar to the guide tube described in FIG.3 b, except the dual wire consumable guide tube 249 receives two weldingwires.

FIG. 4 is a side view of an alternative guide tube in which one strip isflat and the other two strips are roll formed. The guide tube 250comprises a flat strip 252 joined or coupled to roll formed strips 254and 256. By way of example and not of limitation, the roll formed stripsor sheets are 20 to 28 gauge cold roll steel which are bent to a 60°angle. The insulating modules are not shown.

FIG. 5 is alternative embodiments of guide tube designs with flat stripsand formed thin strips. Guide tube 260 comprises a thin strip that isformed to define two 90 degree elbows at the edges of the thin strip;the elbow provide an opening for welding wires 264 and 266. Guide tube270 comprises a thin strip 272 that is formed with rounded edges; therounded edges provide an opening for welding wires 274 and 276. Guidetube 280 comprises two thin strips 282 and 284 which are formed with one90 degree elbow at the edges of each thin strip and providing an openingfor welding wires 286 and 288. Guide tube 290 comprises two flat strips291 and 292 joined to two thin strips 293 and 294 and providing anopening for welding wires 296, 297 and 298. Guide tube 300 comprises athin strip 302 which has one 90 degree elbow at each edge and has adepression in the center of the thin strip 302 that is adjacent the flatstrip 304; the depression and elbows provide an opening for weldingwires 306 and 308.

The present guide tube comprises two low carbon steel strips havinglongitudinal channels, which receive two or more welding wires and haveinsulator modules, which do not increase the depth of the weld puddle.

FIG. 6 a through FIG. 6 d is an alternative embodiment of the guide tubein which both plates are shaped similarly. FIG. 6 a is a top view of aguide tube 340 having a single strip milled or roll-formed to receivetwo wire feeds with staged insulator modules. FIG. 6 a is the front faceof a first elongated strip 341. The first elongated strip 341 has twolongitudinal grooves 342 and 344 that are either milled or roll-formedinto the strip 341 by methods well known in the art of machining orroll-forming. By way of example and not of limitation, the strip 341 is⅛ of an inch thick and is 2 inches wide, and the longitudinal grooves344 are approximately ⅝ of an inch from one another. In its preferredembodiment, the guide tube strip 41 is made of low carbon steel, such asa 1008 carbon steel.

Insulator modules 346 and 348 are disposed at incremental stages on theback face of strip 341. By way of example and riot of limitation,insulator modules 346 and 348 are disposed at intervals of four to sixinches from one another. The selection of the intervals for theinsulator modules is described more thoroughly below. The insulatormodules 346 shown in FIG. 6 a comprise high temperature glue mixed witha welding flux, and the insulator nodules are attached to strip 41 withthe high temperature glue. By way of example and not of limitation, thewelding flux is the same flux used to create the molten electroslag fluxbath and the welding glue is a high temperature glue.

FIG. 6 b is a cross-sectional view of FIG. 6 a. The longitudinalchannels 344 of first strip 341 are spaced evenly apart on the frontface of first strip 341. By way of example and not of limitation, theinsulator module 346 has a diameter of approximately 0.5 inches. Sincethe electroslag process which is hereby incorporated by reference allowsthe guide tube to be oscillated during the welding operation, thethickness of the insulators may vary to allow enough clearance in theweld gap for the guide tube to oscillate.

FIG. 6 c is a front view of two single strips which are joined orsandwiched together. The front view of apparatus 350 is of the back faceof a second strip 351 having milled longitudinal channels 352 and 354 onthe front face and two insulator modules 354 and 356 on the back face.The second strip is joined to the first strip by resistance spot weldingat locations 360, 362, 364 and 366. Those skilled in the art that othertechniques for joining the first strip to the second strip include tackwelding the sides of both strips, or using an adhesive to join bothstrips, shall appreciate it

FIG. 6 d is a cross-sectional view of FIG. 6 c. The cross sectional viewis located at the location 360 where both strips have been resistancespot welded together. Note that the first strip 341 and second strip 351are mirror images of one another and receive two welding wires boundedby channels 342 and 352 and by channels 344 and 354. It shall beappreciated that the guide tube described in FIG. 6 a through 6 d mayreceive more than two welding wires. Additionally, the guide tubedescribed in FIG. 6 a through 6 d can be made of various widths, lengthsand thicknesses.

FIG. 7 a is a cross-sectional view of a guide tube having insulatormodules on the front side and back side of the joined strips. The guidetube 370 has milled or roll-formed longitudinal channels which receivewires 372 and 374. The insulator modules 376 and 378 are attached to theguide tube as described above. The two strips may be joined together byany method which is appreciated by those skilled in the art of joiningmetal strips.

FIG. 7 b a cross-sectional view of a guide tube having insulator moduleson the front, back and the two sides of the joined strips. The guidetube 380 has milled or roll-formed longitudinal channels which receivewires 382 and 384. The insulator modules include modules 386 and 388which are attached to the front and back face of each strip; andinsulator modules 390 and 392 which are attached to the side of theguide tube.

FIG. 7 c is a cross-sectional view of an alternative embodiment in whichthree strips are joined together. Guide tube 400 comprises three strips.The first strip 402 is a flat metal strip. The second strip 404 andthird strip 406 each have longitudinal channels. The second strip 404and third strip 406 are coupled to the first strip 402. The second strip404 coupled to the first strip 402 defines an opening through which wire408 is received. The third strip 406 is coupled to the first strip 402through which wire 410 is received. Insulator modules 412 and 414 arepositioned on the edges or sides of the guide tube.

FIG. 8 is a method 450 for using the guide tube in an electroslagprocess. The guide tube operates in conjunction with an electroslagwelding system which has been previously described and is incorporatedby reference. The method is initiated at block 452 where the programwelding variables are input in a computer. The method then proceeds toblock 454 in which the guide tube is positioned into the welding cavity.After the guide tube is positioned in the weld cavity the methodproceeds to block 456 where the guide tube is attached to a weldingtorch and wire feed conduits. As described by block 458, the weld cycleis then initiated and proceeds to block 460.

At block 460, after the weld cycle is initiated the electroslag processis initiated when a welding arc is struck in the sump. Weld flux isadded to the welding arc until the flux is molten and forms a slag whichrises to the bottom of the guide tube and extinguishes the arc. Once theelectroslag process is underway, the insulators on the guide tube allowthe guide tube to be oscillated to spread the weld metal to the fullwidth of the substrate as shown in block 462. Preferably, multiple wiresare also used to generate a shallows weld puddle to produce a higherform factor and make the weld more crack resistant. At block 464, ashallow weld puddle is generated by the methods described above whichare not limited solely to the feeding of multiple wires into the weldpuddle. At block 466, the operating voltage is minimized to reduce thesize of the heat affected zone. At block 468, once the electroslagwelding process is underway the operating weld speed may be increasedbecause the substrate metal is has been heated. At block 470, theelectroslag weld is completed and the welding cycle is completed, thewire feed is terminated, and the sump is removed and the run off tabsare removed from the top of the weld.

FIG. 9 is a method 480 for manufacturing the guide tube. The preferablemethod for manufacturing the guide tube is engaged at block 482 in whicha first metal strip is selected. The first metal strip is preferably alow carbon cold-rolled steel strip. At block 484, the second stripmaterial is selected, and the second strip is preferably a low carbonhot-rolled steel strip. Alternatively, the first metal strip and secondmetal strip can be made of a low carbon steel or medium carbon steel.Additionally, the first metal strip and second metal strip can becold-rolled steel or hot-rolled steel. It shall be appreciated by thoseof ordinary skill in the art that other types of steel having similarproperties may also be used. The low carbon hot-rolled steel strip isused as the current carrying side of the guide tube, and is, therefore,thicker than the first metal strip. Alternatively, the first metal stripand the second metal strip are the same thickness. The method thenproceeds to block 486.

At block 486, the longitudinal channels or grooves are machined,roll-formed or stamped in the first metal strip. Alternatively, thelongitudinal channels or grooves may be attached to the second metalstrip. The method then proceeds to block 488.

At block 488, the first metal strip which is cold rolled and the secondmetal strip which is hot rolled is joined together to form the guide. Itis preferable, that the guide tube be a multi-wire guide tube whichoscillates during an electroslag weld. The method then proceeds to block490.

At block 490, the insulators are attached to the guide tube. Theinsulators are glued or attached to the to the front and back face ofthe guide tube. Preferably, the insulators are disposed on the guidetube to prevent arcing of the electrode guide tube with the substratemetal and the copper shoes. The insulators may be strip insulators orbutton insulators. The method then proceeds to block 492.

At block 492, the guide tube is tested to make sure the guide tubechannel is configured to receive the appropriately sized welding wire. Arust resistant coating is then applied to the guide, as shown in block494. Finally, at block 496, the guide tube is packaged in shipping boxesto prevent damage to the guide tube and its insulators.

While embodiments and applications of this invention have been shown anddescribed, would be apparent to those skilled in the art that many moremodifications than mentioned above are possible without departing formthe inventive concepts herein. The invention, therefore, is not to berestricted except in the spirit of the appended claims.

1. A consumable guide tube configured to be placed in a weld gap, theguide tube comprising in combination: a first elongated strip and asecond elongated strip wherein each of the strips have a front face anda back face, a length, and two elongated edges; at least onelongitudinal channel having a uniform cross-sectional geometry definedon the front face of the first elongated strip distant from theelongated edges, the longitudinal channel positioned and sized toreceive at least one welding wire; the front face of the first elongatedstrip joined to the front face of the second elongated strip; and aplurality of insulator modules coupled to the back face of the firstelongated strip and the back face of the second elongated strip.
 2. Theguide tube of claim 1, wherein the guide tube is oscillated in anElectroslag welding process.
 3. The guide tube of claim 1, wherein thefirst elongated strip comprises two or more longitudinal channels,wherein each channel has a uniform cross-sectional geometry.
 4. Theguide tube of claim 1, wherein the first elongated strip is joined tothe second elongated strip by welding the first elongated strip with thesecond elongated strip.
 5. The guide tube of claim 1, wherein the atleast one longitudinal channel uniform cross-sectional geometry iscircular.
 6. The guide tube of claim 1, wherein the at least onelongitudinal channel uniform cross-sectional geometry is triangular. 7.The guide tube of claim 1, wherein the first elongated strip is thinnerthan the second elongated strip.
 8. The guide tube of claim 7, whereinthe insulator modules are coupled to the first elongated strip and thesecond elongated strip at intervals.
 9. A consumable guide tube used inan Electroslag process, the consumable guide tube configured to guide atleast one welding wire into a welding cavity and transmits amperage tothe at least one welding wire, comprising: a first elongated strip and asecond elongated strip where the first elongated strip and the secondelongated strip each has a front face and a back face, a length, and twoelongated edges; at least one longitudinal channel having a uniformcross-sectional geometry defined on the front face of the firstelongated strip distant from the elongated edges, the longitudinalchannel positioned and sized to receive at least one welding wire; thefront face of the first elongated strip joined to the front face of thesecond elongated strip; and a plurality of insulator modules coupled tothe first elongated strip and the second elongated strip.
 10. The guidetube of claim 9, wherein the first elongated strip is thinner than thesecond elongated strip.
 11. The guide tube of claim 10, having two ormore channels defined on the first elongated strip.
 12. The guide tubeof claim 11, having a plurality of insulator modules disposed inintervals of 4 to 6 inches.
 13. A consumable guide tube configured to beplaced in a weld gap, the guide tube comprising in combination: a thinfirst elongated strip having a front face and a back face, a length, andtwo elongated edges, wherein the front face has at least onelongitudinal channel having a uniform cross-sectional geometry definedon the front face of the first elongated strip distant from theelongated edges, the longitudinal channel positioned and sized toreceive at least one welding wire; a second elongated strip having afront face and a back face, a length, and two elongated edges, whereinthe front face of the second elongated strip is configured to be coupledto the front face of the thin first elongated strip; and a plurality ofinsulator modules deposited on the back face of the thin first elongatedstrip and on the back face of the second elongated strip.
 14. The guidetube of claim 13, wherein the thin first elongated strip is a low carboncold-rolled steel strip.
 15. The guide tube of claim 13, wherein thesecond elongated strip is a low carbon hot-rolled steel strip.
 16. Theguide tube of claim 13, wherein the thin first elongated strip comprisestwo or more longitudinal channels, wherein each channel has a uniformcross-sectional geometry.
 17. The guide tube of claim 13, comprising arust resistant coating deposited on the guide tube.
 18. The guide tubeof claim 13, wherein the plurality of insulator modules is composed of aflux material used as flux during an Electroslag process.
 19. The guidetube of claim 13, wherein the thin first elongated strip is coupled tothe second elongated strip.
 20. The guide tube of claim 13, wherein thethickness of the combination of the thin first elongated strip, thesecond elongated strip, and plurality of insulator modules is less than0.75 inches.